Drafting equipment



Jan. 31, 1956 H. E. SMITH 2,732,624

DRAFTING EQUIPMENT Filed Jan. 26, 1953 Afaeow 5 5M/ TH 2,1 2,16 'DRAFTING UIPME Harold E. Smith, has, Mat-h. Application January 26, 19 53, Serial No. 333,043 1 Claim. (or. 33-80 This invention relates to facilitating lining or other locations, generally over a plane surface, in general layout operations.

This invention has utility when incorporated in a drawing board, hereunder specially equipped with tracks offset from the board face and extending along parallel edge faces, and a straight-edge of T-square analogy, adapted to coact with tracks in opposed relation, and thus responding to parallel line shifting and position holding for the straight-edge.

Referring to the drawings:

Fig. 1 is a perspective view of a portable drawing board, independent of table or other mounting or support therefor, which board has the automatically parallel straightedge, shiftably associated therewith;

Fig. 2 is a plan view, on an enlarged scale, of antifriction roller system for the straight-edge for shifting along tracks of a drawing board, major portions being suggested in dotted lines;

Fig. 3 is a view in side elevation of the yieldably mounted roller in the set-up, with such roller at outwardly thrown position, but in such position engaging the drafting board track; and

Fig. 4 is an end elevation of the head or T-end of the straight-edge, showing a roller clear of the board track at such end.

A rectangular layout or drawing board or area 1, as of plywood, has screws 2 in slots 3 for adjustable stop or lower side strip 4. Along the right edge of the board 1 is board rigidity and planar holding means or angle metal trim 5 with a groove or track guide 6 adjacent a track face 7 in proximity to the top face of the board 1. Parallel to the trim 5, the left edge of the board 1 is equipped with a similar trim 8 to the trim 5. The trim 8 has its track guide 6 as a border for a track face 7.

A straight-edge practical herein is of oak 7 thick and 2%" wide for a board 1 in the range of 4 spacing between the end trims 5, 8. Definitely specially located and anchored in the straight-edge 9 are screws or pins 10, 11, 12, 13. The screw 10 is central of the length of bar or T-head 14. This bar 14 is held perpendicular or at right angles to the general direction of the straightedge 9 by the second bolt or screw 11. The mid-point screw 10 for the bar 14 is located in proximity to what is normally the upper or usually taken edge for layout work. This makes upper section or arm 15 of the bar 14 of greater extent to its free end 16 than is the other or shorter arm 17 to its free end 18.

The end 16 of the bar 14 has a bolt 19 mounting a roller having a face 20 and a flange 21. Also at the end 18, there is a similar bolt 19 mounting for free rotation a flanged roller 20, 21.

The stems of the pins 10, 11, 12, 13, are screw threaded to receive nuts 22 in assembling the bar 14 and a U-leaf spring 23 with the straight-edge 9 under side, or side toward the board 1. For spacing the under side of the straight-edge 9 from extended area of contact with the board 1, there is spaced inward from the bar 14 and from 2,732,624 Batented Jan. 31, 19.56

. 52 the spring 22}, convex face elements 24,-somewhat ofthe character of the, heads of thumb tacks. v

The leaf spring 23 has a wrap 25 at the pin 12, and a rap 26 at the pin 13. There is thus established a holding for a flex region 27 or U-bend of the spring 23' for swinging of the spring free endarm 28 toward and from the pin 12. The wrap free end of the spring arm 28 has a pin 29 rotatably inounting'therein a third roller 20, 21, which approximates the apex position of an isosceles triangle with the bar 14 as the base, with a median or perpendicular 30 between the pins 10, 29, and equal sides 31 from the apex pin 29 to the bolts 19 at the arm ends 16, 18. The U-form leaf spring is of imperforate body thruout its entire length, with the pin-embracing wraps of greater than semicylindrical extent.

It is to be noted that the median 30, of the isosceles triangle from the triangles apex, is parallel to the margins of the straight-edge 9. The pins 10, 11, 12, 13, of nearly fiat convex exposed upper face or head portions, have tangs 32 from the under fiat sides of such heads, which tangs embed in the face of the wood straight-edge 9 and thereby hold the respective pins from rotation as such pins are drawn to anchoring positions by the nuts 22.

The roller-carrying bolts or elements 19, 29, have at their lower or threaded end portions, nuts 33. In practice, with the plane section or drafting board 1 flat, nearly fiat or horizontal, anti-friction assembly of the straightedge 9 therewith may work out acceptably thru the flanged rollers 20, 21, in the balanced group of three thereof. With the straight-edge 9 poised clear of the area 1, the straight-edge 9 is brought into proximity with the table top 1 (Fig. 3) and the flange 21 of the roller 20, 21, on the spring arm 28 is directed say to ride in the groove 6 at the right, that is, in angle trim 5. The element 29 is then swung toward the pin 12, being in a direction approximating that of the line 30 extended. This action by grasping the straight-edge 9 is sufficient to provide clearance for the T-head bar 14 to be at the left of the trim 6 (Fig. 4) for the flanges 21 of the two rollers carried by the bar 14 to ride into the groove 6, as the straightedge 9 lying against the board 1 is released for the spring 23 to act. The faces 20 of the three rollers now ride on the tracks 7, and all travel of the straight-edge 9 is now controlled in parallel with the side strip 4. Usually draftsmen find its convenient to have the drawing board 1 with an upward tilt as away from the strip 4. The straight-edge 9 may be stabilized against too free shifting toward the strip 4 or movement from a selected working position on the board 1, thru establishing for the spring 23 eflective slack take-up. However, there is still antifriction mounting of the straight-edge 9 by the rollers 20, 21.

What is claimed and it is desired to secure by Letters Patent is:

Drafting equipment comprising a plane portion marginally terminating in a pair of parallel bounds regions, there being first and second lineal seats, one at each bounds region and parallel to the plane portion, a strip of length spanning the plane portion and endwise extending to overlap beyond said regions, said strip having a width-providing side between parallel first and second straight edges, a U-form leaf spring of imperforate body thruout its entire length, said spring forming two legs spaced by a return bend, two strip engaging anchor pins, one of said pins being for one leg end of the spring in proximity to the first straight edge and spaced from the adjacent bounds region at the overlap underside of the strip, said other pin being adjacent the return bend in proximity to the second straight edge at the overlap underside of the strip, a first roller, a strip engaging mounting pin for the first roller on the free end of the other leg of the leaf spring in proximity to the first straight edge of the strip for riding in a bounds first lineal seat, said spring having an integral arc wrap of greater than semicylindrical extent in an embracing assembly at said anchor and mounting pins, second and third rollers anchored with the strip adjacent the second lineal strip, said rollers defining an isosceles triangle with the first roller at the apex and the triangle median in proximity to said first straight edge and remote from the second straight edge of the strip, the spring return bend and third roller being in proximity to the second straight edge of the strip, the second roller being more remote from the first edge than the third roller is from the second straight edge.

References Cited in the file of this patent UNITED STATES PATENTS Carlson Apr. 9, 1918 Boon June 13, 1922 Sieveking Nov. 29, 1938 FOREIGN PATENTS Great Britain Dec. 21, 1893 Great Britain June 13, 1913 Germany Aug. 12, 1936 France Sept. 28, 1942 Austria May 10, 1950 

